This is the software publisher's description.

Wipe utility that lets you securely erase any old (deleted) files and prevent them from being recovered. All your private sensitive insecurely erased information will be wiped from free unused space on your drives to ensure complete data destruction.

This is necessary because when you delete a file, it is not gone forever, and any file removed from the Recycle Bin can be easily recovered! The Windows delete function does not clear the space where the deleted file has been located but only marks an entry in the directory (folder) as deleted. All data and information about the file still remains on the disk and can be restored!

Old data will be available until another file overwrites it (uses the same space on the disk). The only way to prevent data from being recovered is to overwrite it.

The functions that Disk Redactor performs are wiping all free unused space on your disks, and writing a big file with zeros to overwrite all old (deleted) files on your drive. After using Disk Redactor, all old data will be erased completely without any chances for its recovery.

Use Disk Redactor every time you delete files containing your confidential and sensitive data, otherwise this data can be easily recovered.